Founding Product Engineer

About the Role This is a founding engineering role at an early-stage B2B SaaS startup building an AI-driven pricing and monetization platform. You'll own entire product modules end-to-end — from architecture through shipped UI — working directly with customers and leadership to shape the product. Financial precision, technical leadership, and comfort with ambiguity are central to success here. What You'll Do Scope, design, build, and iterate on whole product modules independently, including versioned APIs and React UIs. Design and evolve architecture for agentic AI systems spanning Slack bots, terminal interfaces, web surfaces, and vendor integrations. Ensure features are drivable by LLM agents via MCP/FastMCP servers and conversational interfaces. Move pricing and business logic off the client into backend services to preserve financial fidelity. Extend and maintain a typed pricing ontology using Pydantic models (e.g., SKU, Proposition, Persona, Pricing, Customer, Contract, Quote). Lead architectural reviews and establish testing, observability, deployment, and performance monitoring practices for AI-driven features. Mentor peers, influence product strategy, and help set engineering culture and best practices. Treat money-handling code as load-bearing infrastructure and drive root-cause analysis for production issues. Contribute to an AI-native SDLC where agents assist with code and automated review gates. What We're Looking For 8+ years of software engineering experience with proven ownership of full product areas at startup or staff-level scope. Deep backend expertise with production experience in FastAPI, Python, and MongoDB (or a comparable stack). Credible full-stack range: able to design versioned REST/GraphQL APIs and ship polished React + TypeScript UIs independently. Track record of taking ambiguous customer problems to shipped features without a dedicated PM. Experience with B2B SaaS monetization concepts: pricing models, packaging, quoting, billing, or CPQ. Experience building or integrating AI-assisted features and agent-driven workflows (LLM interfaces, tool-use endpoints, etc.). High standards for correctness, especially around financial logic. Nice to have: Built MCP servers or tooling for LLM agents. Nice to have: Experience with billing, CPQ, metering, or usage-based pricing systems. Nice to have: Familiarity with SOC2/GDPR-compliant development practices. Nice to have: Prior experience as a technical founder or early employee who shipped a 0-to-1 B2B product to paying customers. Must be authorized to work in the United States; visa sponsorship is not available . Compensation & Benefits Salary range: $200,000 – $250,000 USD annually . Equity participation expected at this founding-team scope. Visa sponsorship is not available. Location On-site in San Francisco, CA . Remote work is not available for this role.